1. Field of the Invention
The present invention relates to a dry etching apparatus and method for producing semiconductor devices and Micro-Electro-Mechanical-Systems (MEMS).
2. Description of the Related Art
With the recent increase in the capacity of semiconductor memories and in the speed of semiconductor devices, there is a need for fine processing technology to process silicone and a laminated film of oxide silicon, silicon nitride, and the like, to have a space width of 10 nm and an aspect ratio of 15 or more. Further, under such circumstances, there is a need for etching apparatus using a plasma source capable of generating a plasma with a medium density at low to high pressure, to maintain the throughput (mass productivity) improvement.
A parallel-plate type plasma source is suitable for such a plasma source. The parallel-plate type plasma source generates a plasma in a region between an upper electrode and a lower electrode. Further, the magnetic VHF plasma etching apparatus is known as a dry etching apparatus with a VHF wave of 200 MHz as well as a magnetic generation coil for distribution control.
The magnetic VHF plasma etching apparatus includes a vacuum chamber in which a vertically movable wafer stage (lower electrode), and an antenna electrode (upper electrode) located opposite the vertically movable stage are placed (Japanese Patent. Application laid-Open Publication No. 2005-79416). The magnetic VHF plasma etching apparatus emits VHF radiation at a frequency of 200 MHz from the antenna electrode to ionize the gas within the vacuum chamber into a plasma. At this time, a uniform ion distribution can be achieved by controlling the plasma generation distribution and the plasma diffusion by electromagnets A and B arranged so as to have magnetic field lines in the vertical direction.
The height of the plasma generated between the antenna electrode and the wafer stage on which a wafer is placed, can be changed in a range of 18 to 140 mm by a wafer stage lifting mechanism. The wafer stage includes an RF bias power supply of 4 MHz for drawing ions in order to accelerate the etching reaction, as well as a temperature controller for wafer temperature control.
The VHF plasma etching apparatus with such a configuration can generate a low-dissociation and high-pressure plasma, and is suitable for etching of silicone insulating film using fluorocarbon gas. Gases for plasma generation are introduced into the antenna electrode from a gas inlet port. The introduced gases are concentrically distributed so as not to be mixed together in a gas distribution plate. Then, the gases with different composition ratios are discharged into the vacuum chamber from a shower plate.
The shower plate for insulating film etching uses a low-resistance silicon plate with a large number of openings, in which ions are drawn to the surface of the silicon panel by a bias that an RF power supply for antenna bias oscillates, to achieve a highly-selective insulating film etching by consuming excessive fluorine. At this time, the phases of the RF power supply for antenna-bias and the RF bias power supply are controlled to be 180 degrees, respectively, by a phase control unit based on the detected phases.
There is disclosed a method for using corrosive gases such as Cl2 and HBr in the apparatus described above, by splaying resin or ceramic on the surface to which a pressure of 50 Pa or more is applied between the antenna electrode and the gas distribution plate, and by using a dielectric material for the shower plate (Japanese Patent Application Laid-Open Publication No. 2007-59567).
There is also disclosed a method for providing an electrical property control circuit on the side of the upper electrode facing it, in a capacitively-coupled plasma (CCP) etching apparatus (Japanese Patent Application Laid-Open Publication No. 2011-82180).